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III.G.7. (XIII.B.3.) (XIII.D.5.)

Compare vibrational frequencies for two calculations for HOClO (Chlorous acid)

A = HF/6-31G*

B = MP2/6-31G*

scale factors=0.8985, 0.943
  symmetry   frequency (cm-1)   reduced mass (amu)   IR Intensity (km mol-1)
mode number A B   A B diff. ratio   A B diff. ratio   A B diff. ratio
1 A A   3614 3445 168.9 1.049   1.068 1.068 0.000 1.000   133.50 57.52 75.99 2.321
2 A A   1264 1135 128.5 1.113   1.097 1.133 -0.036 0.968   63.09 86.86 -23.77 0.726
3 A A   778 1102 -323.8 0.706   17.881 10.794 7.087 1.657   92.19 85.68 6.51 1.076
4 A A   747 545 202.4 1.371   15.800 16.953 -1.153 0.932   35.61 148.66 -113.06 0.240
5 A A   384 396 -12.7 0.968   2.753 1.272 1.481 2.164   132.14 153.03 -20.89 0.863
6 A A   267 285 -17.7 0.938   1.668 5.917 -4.248 0.282   62.56 2.06 60.50 30.372
scaled by     0.8985 0.943

See section III.C.1 List or set vibrational scaling factors to change the scale factors used here.
See section III.C.2 Calculate a vibrational scaling factor for a given set of molecules to determine the least squares best scaling factor.